The invention relates to a circuit for operating computing components, in particular microprocessors, of the type including at least one reset device which, as a result of interferences, transmits a reset signal to the computing component, which can have a varied program sequence following the appearance of a reset signal, and wherein the sequence is determined in dependence on a compare signal provided by a comparator. From the EP-A 163 670, a device of the above type is known with two monitoring units for program-controlled arrangements, which detect short-term interferences or system failures and which subsequently transmit a reset signal to the microprocessor. Planned is a varied program is sequence following an occurring reset signal, which sequence is determined depending on a compare signal. The compare signal indicates that a digital number stored in a volatile memory coincides at least in part with a digital number stored in a fixed memory. If they coincide for the most part, it is assumed that the reset signal was triggered by a monitoring unit, which has emitted the reset signal, for example as a result of a high-frequency interference. If, however, it is determined that the two digital numbers do not have a common pattern, it is assumed that the reset signal was triggered by another monitoring unit, which emits a reset signal, for example during the startpup on the device. The program sequence that varies as a result of the comparison, if applicable permits a considerable shortening of the program restart time in that, for example, it is not necessary to have a complete initialization of the registers and that, for example, a new loading of the user programs or other operations need not be carried out.
The present invention comprises a circuit for operating computing components, in particular microprocessors, with the circuit including at least one reset device which, as a result of interferences, transmits a reset signal to the computing component which can have a varied program sequence following the appearance of a reset signal, with the sequence being determined in dependence on a compare signal provided by a comparator, and wherein the comparator compares a signal that reflects the condition of a device which is triggered by the computing component with at least one threshold value.
The circuit according to the invention for operating computing components, in particular microprocessors, has the advantage that the differences in the program sequence depend on the condition of a device which is controlled by the computing component. Taking into consideration the condition of the device makes it possible to distinguish between a reset signal which has appeared, for example, as a result of electromagnetic interferences and another reset signal. By taking into account the condition of the device, undesired operating situations in particular are avoided.
Advantageous improvements and embodiments of the inventive circuit for operating computing components, in particular microprocessors, result from dependent claims.
The circuit according to the invention is suited especially for a computing component that controls an adjustment drive activated by an electric motor. The signal corresponding to the condition of the device, which is compared by a comparator with at least one preset threshold value, is for an adjustment drive preferably of the position of the component that must be adjusted. For an adjustment drive that is operated by an electric motor, increased electromagnetic interferences through the increased motor current must be expected, especially when reaching mechanical limit stops, which may, if necessary, lead to a blocking of the electric motor. Having knowledge of the position of the component to be adjusted and once the reset signal appears, the decision can be made with the comparator on whether the program is to branch out to a complete initializing or to a considerably shortened restart point within the program.
An initializing provides, for example, for a calibration run of the adjustment drive, wherein an incremental position measuring system learns the stop positions of the adjustment drive. If it is recognized that the re set signal has appeared as a result of reaching one of the stop positions, then the calibration run preferably can be dispensed with.
The circuit according to the invention is suited especially for operating computing components, which control an adjustment drive arranged in a motor vehicle. Adjustment drives are used, for example, for different vehicle body components such as seat/mirror adjustment, window opener and sun roofs. Another use is in fuel dosing systems, especially for the adjustment of a butterfly valve controlled by an electric motor in the fuel dosing system of an internal combustion engine. For such adjustment drives, it is particularly advantageous if the calibration run, for example, is not performed for each occurrence of a reset signal.
One embodiment of the circuit according to the invention provides that the program sequence is additionally fixed by the number of occurring reset signals. This measure ensures that a predetermined number of reset signals occurring as a result of electromagnetic interferences will definitely lead to a program sequence, which includes, for example, the previously mentioned calibration run.
Other advantageous embodiments and improvements of the circuit according to the invention for operating computing components, in particular microprocessors, result from further dependent claims and from the following description.